Cable television is a system in which signals from stations are converged toward a main station as a center. The signals from stations are gathered together at the main station which functions as a transmitter, then the converged signals (so called the primary signals) are delivered to a local network via a transmission cable, and signal couplers are connected to a primary signal transmission cable to deliver signals to clients (paying subscribers).
At present, when opening a cover of the conventional signal coupler for maintenance purpose, power supply and signals are interrupted, so the paying subscribers cannot watch the television programs well, which is a main shortcoming of the conventional signal coupler. There is already an uninterruptible signal coupler in the market, which prevents disconnection between the power/signal input end and the power/signal output end when the cover is opened for repairing/replacing a circuit board or other components; however, it is not easy to make accurate alignment in the structure, so signal transmission problem occurs.